Wellbore circulation assembly

ABSTRACT

In some embodiments, a circulation assembly can direct all or substantially all fluid downstream in a drill string in a first mode of operation, and some or all fluid to an annulus in a second mode. Operation of the circulation assembly can be repeatedly changed between the modes of operation. In some embodiments, the circulation assembly can comprise other modes wherein fluid is apportioned between the annulus and the downstream drill string.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119 of U.S. Provisional Patent Application Ser. No. 61/234,935, entitled “WELLBORE CIRCULATION ASSEMBLY,” filed on Aug. 18, 2009; and U.S. Provisional Patent Application Ser. No. 61/236,053, entitled “WELLBORE CIRCULATION ASSEMBLY,” filed on Aug. 21, 2009. Each of the above-identified applications is hereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present invention generally relates to control of fluid flow in downhole systems and, in some embodiments, to methods and assemblies for controlling the flow of fluid within coiled tubing systems in particular.

BACKGROUND OF THE DISCLOSURE

Downhole operations routinely encounter pump rate limitations due to surface pressures exceeding the capacity of the pumps or the tubing. High surface pressures can be attributed to a variety of sources such as fluid weight, frictional loss, and pump rate. This problem is exacerbated when the downhole tools being used create additional back pressure or have rate limitations. These tools can include, for example, positive displacement motors (PDM), hydraulic tractors, and multi-lateral entry tools (MLT).

SUMMARY OF THE DISCLOSURE

In some embodiments, a circulation assembly can direct all or substantially all fluid downstream in a drill string in a first mode of operation, and some or all fluid to an annulus in a second mode. Operation of the circulation assembly can be repeatedly changed between the modes of operation. In some embodiments, the circulation assembly can comprise other modes wherein fluid is apportioned between the annulus and the downstream drill string. The circulation assembly can be an independent subassembly of a drill string, or form a part of equipment that also performs other functions.

In one embodiment, a flow management assembly for selectable direction of working fluid in an hydraulic system for well operation can comprises a fluid inlet, a first fluid outlet, a first passage, a second fluid outlet, a second passage, and a valve. The fluid inlet is positioned at an upstream end of the assembly and configured to receive fluid from an upstream component of the system. The first fluid outlet is positioned at a downstream end of the assembly and configured to deliver fluid to downstream component of the system. The first passage connects the fluid inlet to the first fluid outlet. The second fluid outlet is configured to discharge fluid from the system. The second passage connects the fluid inlet to the second fluid outlet. The valve is movable repeatedly between a first configuration and a second configuration. In the first configuration, discharge of fluid from the system through the second fluid outlet is inhibited. In the second configuration, the discharge of fluid from the system through the second fluid outlet is greater than in the first configuration.

In one embodiment, a method for directing fluid flow within an hydraulic system for operation in a wellbore comprises the steps of receiving fluid from an upstream component of the system, directing the fluid toward a downstream component of the system, opening a passage to discharge at least a portion of the fluid from the system, and closing the passage to direct all of the fluid toward the downstream component.

In one embodiment, a downhole assembly comprises a coiled tubing drill string, a circulation assembly, and at least one of a tractor and a bottom hole assembly. The circulation assembly comprises an upstream connector, a downstream connector, a first passage, a second passage, a valve and an index mechanism. The first passage extends between the upstream connector and the downstream connector. The second passage extends between the upstream connector and an exterior of the system. The valve communicates with the second passage. The index mechanism is configured to operate in cooperation with the valve.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the major components of a coiled tubing drilling system having gripper assemblies.

FIG. 2 is a schematic diagram illustrating the operation of a circulation assembly according to an embodiment.

FIG. 3 is a cross-sectional plan view of a circulation assembly according to an embodiment.

FIG. 4 is an enlarged view of portion IV-IV, shown in FIG. 3.

FIG. 5 is a schematic diagram illustrating the operation of a circulation assembly according to an embodiment.

FIG. 6 is a schematic diagram illustrating the operation of a circulation assembly according to an embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

FIG. 1 shows a coiled tubing system 20 for use within a passage. The coiled tubing drilling system 20 may include a power supply 22, tubing reel 24, tubing guide 26, tubing injector 28, and coiled tubing 30, all of which are well known in the art. The system 20 can be used in conjunction with various other types of equipment, for example, one or more tractors 50 and a bottom hole assembly 32. The coiled tubing 30 and downhole equipment form a drill string. The coiled tubing system can be used with a circulation assembly 100 that directs flow received from upstream in the drill string to one or both of downstream equipment and an annulus 40, which is defined by the space between the drill string and an inner surface 42 of the passage. Although specific embodiments are herein described in the context of coiled tubing systems, embodiments can be used with other types of drill strings, including jointed tubing and drill pipe.

With continued references to FIG. 1, the system 20 can be used with at least one downhole tractor 50 for moving the system 20. In some embodiments, multiple tractors can be connected end-to-end may allow the use of smaller tractors, thereby facilitating maneuvering the coiled tubing system through a passage with relatively small radius turns. Although two downhole tractors 50 connected end-to-end are preferred in some applications, those of skill in the art will understand that a single tractor 50, or more than two tractors 50 could be used.

The tractor 50 can have one or more gripper assemblies in some embodiments. Those of skill in the art will understand that any number of gripper assemblies may be used. Various embodiments of the gripper assemblies are shown and described in U.S. Pat. No. 6,464,003, filed on Feb. 6, 2001, entitled “GRIPPER ASSEMBLY FOR DOWNHOLE TRACTORS;” U.S. Pat. No. 6,715,559, filed on Dec. 3, 2001, entitled “GRIPPER ASSEMBLY FOR DOWNHOLE TRACTORS;” U.S. Pat. No. 7,392,859, filed on Mar. 17, 2005, entitled “ROLLER LINK TOGGLE GRIPPER AND DOWNHOLE TRACTOR;” U.S. Patent Application Publication No. 2007-0209806, filed on Mar. 8, 2007, entitled “EXPANDABLE RAMP GRIPPER;” U.S. Patent Application Publication No. 2008-0149339, filed on Nov. 13, 2007, entitled “VARIABLE LINKAGE ASSISTED GRIPPER;” all of which are hereby incorporated herein by reference, in their entirety.

It should be noted that gripper assemblies may be used with a variety of different tractor designs, including, for example, (1) the “PULLER-THRUSTER DOWNHOLE TOOL,” shown and described in U.S. Pat. No. 6,003,606 to Moore et al.; (2) the “ELECTRICALLY SEQUENCED TRACTOR,” shown and described in U.S. Pat. No. 6,347,674 to Bloom et al.; (3) the “ELECTRO-HYDRAULICALLY CONTROLLED TRACTOR,” shown and described in U.S. Pat. No. 6,241,031 to Beaufort et al.; (4) the intervention tractor or “TRACTOR WITH IMPROVED VALVE SYSTEM” shown and described in U.S. Pat. No. 6,679,341 to Bloom et al and U.S. Pat. No. 7,121,364, all of which are hereby incorporated herein by reference, in their entirety.

A bottom hole assembly 32 may be assembled with the tractor 50. The bottom hole assembly may include a measurement while drilling (MWD) system 34, downhole motor 36, drill bit 38, and various sensors, all of which are also known in the art. For example, the drilling system 20 can include sensors and sensor assemblies such as those shown and described in U.S. Pat. No. 6,367,366 to Bloom et al, entitled “SENSOR ASSEMBLY.” The tractor 50 is configured to move within a borehole having the inner surface 42.

In some embodiments, the circulation assembly 100 is an independent subassembly that can be joined with other equipment in a drill string, as schematically illustrated in FIG. 1. Such embodiments are referred to herein as circulation subs. In some embodiments, the circulation assembly can be a part or subassembly of another piece of equipment. For example, the circulation assembly can comprise a portion of a tractor. In some embodiments, the circulation sub may be used in a system without a tractor.

In some embodiments, the circulation assembly 100 directs all or substantially all fluid downstream in the drill string in a first mode of operation, and some or all fluid to the annulus 40 in a second mode. In some embodiments, operation of the circulation assembly 100 can be repeatedly changed between the modes of operation. In some embodiments, the circulation assembly can comprise other modes wherein fluid is apportioned between the annulus 40 and the downstream drill string.

In some embodiments, the circulation assembly 100 responds to pressure cycles to change modes. For example, the circulation assembly can open every other pump cycle in some embodiments. In some embodiments, the circulation assembly can have the ability to open and close the circulation ports as many times as needed.

In the first mode, all or substantially all fluid desirably passes unobstructed through the circulation assembly. In some embodiments, a path to annulus is opened while maintaining downstream flow in the second mode. In some embodiments, the circulation assembly can comprise a mode wherein downstream flow is substantially or completely restricted such that all or substantially all fluid is directed to the annulus.

In some embodiments, the circulation assembly can have two distinct modes: circulation ports open, circulation ports closed. In some embodiments, the circulation assembly does not require a ball drop in order to actuate between the two modes, rather it responds to pressure cycles. In some embodiments, the circulation ports on the circulation assembly can open every other pump cycle. The circulation assembly can have the ability to open and close the circulation ports as many times as needed. During the “circulation ports open” mode a direct path to annulus can be opened while the downstream path is unaffected. During the “circulation ports closed” mode all fluid can be directed downstream.

A circulation assembly that can repeatedly open and close fluid flow to the annulus 40 can improve the efficiency of various downhole operations and is, therefore, of significant benefit to intervention and drilling operations. The circulation assembly advantageously can be used in conjunction with downhole tools that either respond to or produce back pressure. Surface pump rates are commonly reduced when there are downhole tools that produce back pressure. The circulation assembly can direct flow to the annulus when a higher flow rate is desirable, then later redirect all fluid downstream so that the other tools can resume their normal operation.

FIG. 2 schematically illustrates operation of a hydraulic circuit within some embodiments of the circulation assembly 100. In the illustrated embodiment, fluid enters the circulation assembly through a fluid inlet 102 and is then divided between a valve passage 104 and a bypass flow passage, such as a parallel flow passage 106. Fluid that enters the valve passage 104 applies pressure on a valve spool 108 which reacts against a valve spring 122. In some embodiments, the hydraulic circuit includes a valve index mechanism, described in greater detail below. When the valve is closed, the fluid is directed solely through the parallel flow passage 106. When the valve is opened, as shown in FIG. 2, fluid is permitted to escape to the annulus 40 (FIG. 1) through the exit passage 112.

The valve index mechanism 110 desirably has at least a first position and a second position. If the valve index mechanism is in the first position, movement of the valve may be restricted and flow through the valve may be substantially or completely restricted. If the valve index mechanism is in the second position, the valve may be allowed open and fluid may exit the circulation assembly to the annulus. In some embodiments, the valve will remain open until the pressure is reduced sufficiently that the valve closes. If the pressure is then increased the valve index mechanism desirably will be in the first position and restrict the movement of the valve such that the valve is restricted from opening. As a result, in this embodiment, all fluid flows through the parallel flow passage 106 to other elements in the drill string, such as the bottom hole assembly. If pressure is reduced and then increased, the process is repeated.

FIG. 3 is a cross-sectional view of a Repeating Circulation Sub (RCS) according to one embodiment, which operates in the manner described in connection with FIG. 2. The illustrated RCS comprises a housing 113 with an upstream connector 114 at one end and a downstream connector 116 at the other end. The upstream connector 114 can comprise an inlet 102. The upstream connector 114 can be a box connector in some embodiments, as illustrated in FIG. 3. The downstream connector 116 can comprise an outlet 126 to downstream equipment. The downstream connector 116 can be a pin connector in some embodiments, as illustrated in FIG. 3. The inlet 102 can be connected to the outlet 126 by a parallel flow passage 106. The inlet 102 and the annulus 140 can be connected by a valve passage 104.

The RCS illustrated in FIG. 3 further comprises a flow divider 118 at a location downstream from the inlet 102, which divides the fluid flow between the valve passage 104 and the parallel flow passage 106, a valve 120, a valve index mechanism 110, a valve spring 122, and a pressure compensated oil chamber 124. In some embodiments, each of these components of the RCS contributes to the function of the assembly.

The valve 120 is positioned to open and close the valve passage 104 to fluid flow. When the valve is open, fluid may flow outside the RSC to the annulus through a portion 112 of the valve passage 104. In some embodiments, pressure acting on the valve 120 can be reacted by the valve spring 122 through the valve index mechanism 110, as illustrated in FIG. 3. The force applied by valve spring 122 can determine the pressure at which the valve opens.

The valve index mechanism 110 can alternately allow the valve to open to vent fluid to the annulus and prevent the valve from opening. One of skill in the art will appreciate that a variety of index mechanisms could be used, including those shown and described in U.S. Pat. No. 7,121,364, entitled “TRACTOR WITH IMPROVED VALVE SYSTEM,” which is hereby incorporated herein by reference in its entirety.

The valve index mechanism 110 and valve spring 122 can be submerged in oil (hydraulic or other) within a sealed chamber 124 providing lubrication. This chamber 124 can be pressure compensated. The pressure compensated oil chamber 124 can be bounded by a piston 128 at one end that is exposed to downhole hydrostatic and formation pressure. In such an arrangement, the piston 128 can desirably move freely to adjust for changes in pressure that occur as the tool travels from the surface to the bottom of the hole. Thus, in some embodiments, each of these components interacts with the others to allow the RCS to alternately open and close its circulation ports.

One of skill in the art will appreciate that other pressure compensation methods and devices could be employed. Further details regarding pressure compensated oil chambers are shown and described in U.S. Pat. No. 6,347,674 to Bloom et al., entitled “ELECTRICALLY SEQUENCED TRACTOR,” and U.S. Pat. No. 6,464,003, entitled “GRIPPER ASSEMBLY FOR DOWNHOLE TRACTORS,” both of which are hereby incorporated by reference in their entirety.

FIG. 4 is an enlarged cross-sectional view of the valve 120 and valve index mechanism 110 of the portion IV-IV of FIG. 3. Fluid that enters the valve passage 104 (FIG. 3) applies pressure on the valve spool 108, which is reacted through the valve index mechanism 110. In one embodiment, in a first position of the valve index mechanism, the valve index mechanism 110 inhibits or restricts movement of the valve spool 108 such that fluid flow is inhibited or prevented. In a second position, the valve index mechanism allows the valve to open and fluid exits to annulus. The valve 120 remains open until the pressure applied to the valve spool 108 is sufficiently reduced that the valve closes. When the pressure is again increased, the valve index mechanism 110 is in the first position and, therefore, movement of the valve spool 108 is restricted such that the valve 120 is not allowed to open. In this mode, all fluid flows through the parallel flow passage 106 (FIG. 3) to other elements in the drill string. If pressure is reduced and then increased, the process repeats itself.

An exemplifying specification has a tool outer diameter of 3.375 in., a tool inner (passage) diameter of 0.75 in., a subassembly length of 20 in., and a design flow rate of 0-4 BPM. This exemplifying specification is designed for a wide variety of coiled tubing operations including acidizing, sandwashing, logging, moving sliding sleeves, drilling, running perforation guns, milling, and other typical operations performed in cased and open hole with restrictions of 3.5 inches or greater. A wide range of variations on size and performance can be achieved to meet a particular application. These variations include changes to flow passages, valve sizes, valve spring (set point), oil type and chamber size (for depth correction), material selection, connection type, and inserting a nozzle 130 into the parallel flow passage 106, such as is shown schematically in FIG. 5. Outer diameters larger and smaller than 3.375 in., are be used in some applications. For example, the outer diameter is 3.50 in. in some embodiments, while in other embodiments the outer diameter is 3.00 in.

FIG. 6 schematically illustrates operation of a circulation assembly according to some embodiments, which isolates downstream flow when in a “circulation ports open” mode such that all or substantially all fluid is delivered to the annulus. Fluid entering through the inlet 102 is directed through to the valve passage 104. The fluid applies pressure on a valve spool 108 which reacts against a valve index mechanism 110. When the valve 120 is in the position shown in FIG. 6, all or substantially all fluid is directed to the downstream outlet 126. When the valve is actuated, fluid is permitted to escape to the annulus 40 through the exit passage 112.

In some embodiments, the circulation assembly can receive and pass a ball to downstream equipment, for example, to actuate tools in the bottom hole assembly. For example, the parallel flow passage 106 of the circulation assembly can have a sufficient diameter to allow the ball to pass therethrough.

In some embodiments, the circulation assembly can comprise passages to allow wireline, fiber optic cable, or other communication to pass through the circulation for communication with equipment located farther downhole.

The circulation assembly can be an independent subassembly of a drill string that can be connected with other equipment in various configurations, such as the above-described RCS. Thus, the RCS may be installed in a bottom hole assembly as a single component or it may be used with other components. Those other components include, but are not limited to one or more of the following: tractors, nozzle subs, anti-stall (downhole motor) tools, various logging tools, perforation guns, sand washing tools, measurement-while-drilling tool, logging-while-drilling tools (e.g., gamma, neutron, resistivity, thermal measurement), downhole motors, drill bits, milling bits, steering assemblies, and special actuation tools such as tools to move sliding sleeves. The RCS may be used with other components including ones provided by various suppliers such as BJ Services, Schlumberger, Halliburton, Baker Hughes, and Weatherford.

For example the RCS, a tractor, and a nozzle sub may be used together. When the RCS is in “circulation ports closed” mode, flow is directed through the parallel passage to the nozzle sub. A differential pressure between the inside and outside of the tubing is created providing power for the tractor to operate. When the RCS is in “circulation ports open” most of the fluid flow will exit to annulus through the RCS. Differential pressure will be minimal between the inside and outside of the tubing so the tractor will remain off. The tractor can be used to convey tubing past its lock up to various depths where the RCS can be “opened” to deliver stimulation treatments, injectivity tests, or perform hole cleaning.

In a further example, the RCS can be used with a motor and mill to facilitate milling of bridge plugs in casing. Typically a substantial amount of “junk” is left in the hole after a bridge plug has been milled because pump rates are limited by pressure and the maximum rate the motor can handle. With the RCS in the bottom hole assembly, after the bridge plug is milled through the circulation ports can be opened and pump rate increased to improve hole cleaning while protecting the motor from damage. This process will result in a cleaner hole with the potential for improved production over a longer period of time.

Although specific exemplifying embodiments have been described as independent drill string subassemblies, the circulation assembly in some embodiments forms an integrated part of a tool such as, for example, a tractor, nozzle sub, logging tool, perforation gun, sand washing tool, measurement-while-drilling tool, logging-while-drilling tool, downhole motor, or special actuation tool such as a tool to move sliding sleeves.

The circulation assembly is preferably constructed from materials that are acid resistant and erosion resistant. For example, Inconel and beryllium-copper metals can be used in the connectors, diverter, and housing of the tool; MP35N or Eligiloy can be used for the valve spring; tungsten carbide can be used in the valve, and seals can be made from commercially available elastomers. The materials of the circulation assembly are also preferably non-magnetic.

Although specific embodiments and examples have been illustrated and described, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. Further, the various features shown and described can be used alone, or in combination with other disclosed features in configurations other than as expressly described above. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow. 

1. A flow management assembly for selectable direction of working fluid in an hydraulic system for well operation, the assembly comprising: a fluid inlet at an upstream end of the assembly configured to receive fluid from an upstream component of the system; a first fluid outlet at a downstream end of the assembly configured to deliver fluid to downstream component of the system; a first passage connecting the fluid inlet to the first fluid outlet; a second fluid outlet configured to discharge fluid from the system; a second passage connecting the fluid inlet to the second fluid outlet; a valve movable repeatedly between a first configuration wherein discharge of fluid from the system through the second fluid outlet is inhibited and a second configuration wherein the discharge of fluid from the system through the second fluid outlet is greater than in the first configuration.
 2. The assembly of claim 1, wherein the discharge of fluid through the second passage is substantially prevented when said valve is in the first configuration.
 3. The assembly of claim 1, wherein the valve comprises a spring that biases the valve to the closed configuration.
 4. The assembly of claim 1, wherein the valve is operable at least partially in response to upstream pressure of the working fluid.
 5. The assembly of claim 1, wherein the valve is operable in a first mode wherein the valve is responsive to increase of upstream pressure to move the valve to the open configuration, and a second mode wherein the valve is not responsive to increase of upstream pressure to move the valve to the open configuration.
 6. The assembly of claim 5, wherein the valve comprises an index to switch the operation of the valve between the first mode and the second mode.
 7. The assembly of claim 1, further comprising a pressure compensated chamber operatively connected to the valve.
 8. The assembly of claim 1, wherein said valve is operable from outside of the wellbore when the assembly is positioned within the wellbore.
 9. The assembly of claim 1, wherein said valve is changeable from said first configuration to said second configuration in response to pressure changes.
 10. The assembly of claim 1, wherein said valve is positioned at least partially within said second passage.
 11. The assembly of claim 1, wherein delivery of fluid to the downstream component through the first fluid outlet is inhibited in the second configuration.
 12. The assembly of claim 11, wherein delivery of fluid to the downstream component through the first fluid outlet is substantially prevented in the second configuration.
 13. A method for directing fluid flow within an hydraulic system for operation in a wellbore, comprising: receiving fluid from an upstream component of the system; directing the fluid toward a downstream component of the system; opening a passage to discharge at least a portion of the fluid from the system; closing the passage to direct all of the fluid toward the downstream component.
 14. The method of claim 13, wherein the passage is opened in response to an increase in upstream pressure of the fluid.
 15. The method of claim 14, wherein the passage is closed in response to a decrease in the upstream pressure of the fluid.
 16. The method of claim 15, wherein after the passage has been opened, the passage is reopened in response to an increase of upstream pressure only after a series of upstream pressure changes comprising an increase in the upstream pressure, and a subsequent decrease in the upstream pressure.
 17. The method of claim 13, further comprising reopening the passage.
 18. The method of claim 13, further comprising adjusting a value of the upstream pressure at which the passage is opened based at least partially on a pressure exterior to the system.
 19. The method of claim 13, wherein the hydraulic system comprises one of coiled tubing, jointed tubing, and drill pipe
 20. The method of claim 13, wherein fluid is directed toward the downstream component of the system, which comprises one of a tractor, a nozzle sub, an anti-stall tool, a logging tool, a perforation gun, a sand washing tool, a measurement-while-drilling tool, a logging-while-drilling tool, a downhole motor, a drill bit, a milling bit, a steering assembly, and a special actuation tool.
 21. A downhole assembly, comprising: a coiled tubing drill string; a circulation assembly comprising an upstream connector, a downstream connector, a first passage between the upstream connector and the downstream connector, a second passage between the upstream connector and an exterior of the system, a valve communicating with the second passage, an index mechanism configured to operate in cooperation with the valve; and at least one of a tractor and a bottom hole assembly.
 22. The downhole assembly of claim 21, wherein the circulation assembly further comprises a flow divider at an intersection of the first passage and the second passage.
 23. The downhole assembly of claim 21, wherein the circulation assembly further comprises a pressure compensated chamber configured to apply pressure to the valve in opposition to pressure asserted on the valve by fluid within the second passage.
 24. The downhole assembly of claim 23, wherein the index mechanism is positioned between the valve and the pressure compensated chamber.
 25. The downhole assembly of claim 21, wherein the bottom hole assembly comprises at least one of a nozzle sub, a logging tool, a perforation gun, a sand washing tool, a drilling tool, a motor, a drill bit, and a milling bit.
 26. The downhole assembly of claim 21, comprising a tractor, the tractor being directly connected to the circulation assembly.
 27. The downhole assembly of claim 21, comprising a tractor, the tractor being spaced from the circulation assembly. 